21 years ago I used it with Apple’s iSync to sync contacts with my flip phone. Later with my iPhone.
I have some lists set up to sort out family, work, etc. I just looked and this can _finally_ be done on iOS as well. It was a Mac-only feature for far too long.
Inside the Apple ecosystem everything assumes use of the Contacts app, so I’ve never really had to think about using anything else. Back when AIM was a thing, I could use Address Book to add people’s screen names and they’d show up in iChat (AIM is dead, but I still have their old screen names in my Contacts app). It supports adding social profiles, URLs, and creating relationships. I can add their birthdays and they show up in the Calendar. It’s always been pretty seamless and hasn’t left me wanting. It’s been pretty nice, but I wouldn’t call myself a heavy user.
At work I don’t manage contacts. We have Outlook with Exchange and I just use the directory of everyone to send the occasional email. LinkedIn is just LinkedIn; I rarely look at it.